Communication System

ABSTRACT

A method of transmitting a communication event from a calling entity to a called entity located in a communication system comprising a first network and a second network, said method comprising determining a first identity associated with the calling entity and a first and second identity associated with the called entity, wherein the first identities are recognizable in the first network and the second identity is recognizable in the second network; associating at a first node located in the second network the first identities with the second identity; establishing a connection between the calling entity and a second node; wherein the connection with second node is established using the first identity associated with the called entity; querying the first node with the first identity associated with the called entity and the first identity associated with the calling entity to determine the second identity associated with the called entity; and transmitting the communication event to the called entity using the second identity associated with the called entity.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/986,977, filed Nov. 27, 2007, which claims priority under 35 U.S.C.§119 or 365 to Great Britain Application No. 0623621.0, filed Nov. 27,2006 and Great Britain Application 0723120.2 filed Nov. 23, 2007. Theentire teachings of the above applications are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a method for handling communication ina communication system.

BACKGROUND

Communication systems link together two communication devices so thatthe devices can send information to each other in a call or othercommunication event. Information may include voice, text, images orvideo.

One such communication system is a peer to peer system, in which aplurality of end users can be connected for communication purposes via acommunications structure such as the interne. The communicationsstructure is substantially decentralised with regard to communicationroute switching therein for connecting the end users. That is, the endusers can establish their own communication routes through the structurebased on exchange of one or more authorisation certificates (useridentity certificates—UIC) to acquire access to the structure. Thestructure includes an administration arrangement issuing thecertificates to the end users. Such a communication system is describedin WO 2005/009019.

Peer-to-peer systems and other communication systems that use theinternet or any other packet switched network employ voice over IP(internet protocol) protocols (VoIP) to transmit data. These systems arecommonly referred to as VoIP systems. VoIP systems are beneficial to theuser as they are often of significantly lower cost than communicationnetworks, such as fixed line or mobile networks, otherwise referred toas public switched telephone networks (PSTN). This may particularly bethe case for long distance calls.

The connection of two communication devices using more than one type ofcommunication network is becoming increasingly common. In some cases acall may be transmitted via more than one network in an attempt toreduce the cost of the call. For example a call between two deviceslocated in a PSTN network may be transmitted via the internet. In othercases it is necessary to transmit the call via two communicationnetworks when each device is located in a different communicationnetwork.

In order to place a call from a device located in one network, such as aPSTN network, to a device located in a different network, such as oneconnected to the internet, it is necessary for the user of the deviceconnected to the internet to register for a PSTN dial in number with thenetwork provider so that calls can be made to the internet user fromdevices in the PSTN network.

One disadvantage of this arrangement is that a device in the PSTNnetwork can only place calls to devices connected to the internet if theuser of the device has registered to have a PSTN number. A furtherdisadvantage of this arrangement is that even if the internet user hasregistered to have a PSTN number, the user in the PSTN network may onlycall the user connected to the internet if he is aware of the PSTNnumber registered to the internet user.

SUMMARY

It is therefore an aim of embodiments of the invention to address atleast one of the above identified problems.

According to a first aspect of the present invention there is provided amethod of transmitting a communication event from a calling entity to acalled entity located in a communication system comprising a firstnetwork and a second network, said method comprising the steps of:determining a first identity associated with the calling entity and afirst and second identity associated with the called entity, wherein thefirst identities are recognizable in the first network and the secondidentity is recognizable in the second network; associating at a firstnode located in the second network the first identities with the secondidentity; establishing a connection between the calling entity and asecond node; wherein the connection with second node is establishedusing the first identity associated with the called entity; querying thefirst node with the first identity associated with the called entity andthe first identity associated with the calling entity to determine thesecond identity associated with the called entity; and transmitting thecommunication event to the called entity using the second identityassociated with the called entity.

According to a second aspect of the present invention there is provideda communication system comprising a first network and a second network,wherein the communication system is arranged to transmit a communicationevent from a calling entity to a called entity located in thecommunication system, said communication system comprising: a firstnetwork node located in the second network arranged to determine a firstidentity associated with the calling entity and a first and secondidentity associated with the called entity, wherein the first identitiesare recognizable in the first network and the second identity isrecognizable in the second network; and to associate the firstidentities with the second identity; and a gateway node arranged toreceive a connection established by the calling entity wherein theconnection is established using the first identity associated with thecalled entity; wherein the first node is further arranged to provide thesecond identity associated with the called entity in response toreceiving the first identity associated with the called entity and thefirst identity associated with the calling entity from the gateway node,such that the gateway node may transmit the communication event to thecalled entity using the second identity associated with the calledentity.

Since the caller is allocated a PSTN number to establish a call toanother party, there is no need for the caller to have prior knowledgeof a fixed PSTN number that is used by the other party to receive calls.

A further advantage of embodiments of the present invention is thatsince both the caller identity and the allocated PSTN number are used toidentify the called party, the same PSTN number may be allocated for useby more than one caller.

As the PSTN number is allocated to a caller for the duration of asession, the caller may make more than one call the same party during asession without requiring a new number each time the call isestablished.

A further advantage of embodiments of the present invention is that noinformation is required to be transmitted from the calling device inorder to establish a call after a connection has been established withthe PSTN network.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention and as to how thesame may be carried into effect, embodiments of the present inventionwill now be described by way of example only with reference to thefollowing drawings:

FIG. 1 is a schematic representation of a communication network inaccordance with an embodiment of the invention;

FIG. 2 a is a diagram showing the protocol stack of a client program inaccordance with an embodiment of the present invention;

FIG. 2 b is a schematic diagram showing the transmission of data betweenthe client protocol stack and the GSM protocol stack in a user device inaccordance with an embodiment of the present invention;

FIG. 3 is a schematic representation of part of the communicationnetwork shown in FIG. 1;

FIG. 4 is a schematic representation of part of the communication systemshown in FIG. 1 according to an embodiment of the present invention;

FIG. 5 shows the call connections made when placing calls between a userdevice and entities located in the communication system according to anembodiment of the present invention.

FIG. 6 shows the logical connections between a call manager, a sessionnode, an inbound gateway and an outbound gateway according to anembodiment of the present invention; and

FIG. 7 is a diagram showing the initiation of a call in accordance withan embodiment of the present invention.

DETAILED DESCRIPTION

Reference will first be made to FIG. 1, in which is shown acommunication network 100, including a packet switched network 104 andcircuit switched networks 112 and 120. In one embodiment the packetswitched network 104 may be the internet. Data may be transmitted viathe internet 104 via a peer to peer system. The circuit switchednetworks 112, 120 may be PSTN (Public Switched Telephone Network)networks.

A user device 102 is shown to be connected to the internet 104 via asession node 106. The user device 102 is also connected to the PSTNnetwork 120. In one embodiment of the invention the user device isconnected to the PSTN network 112 via a circuit switched connection 222and to the session node 106 via a packet switched connection 111. Thecircuit switched connection 222 and the packet switched connection 111may be provided by a GSM (Global System for Mobile Communications)network (not shown). For example the packet switched connection may beprovided by a GPRS (General Packet Radio Service) connection of the GSMnetwork whilst the circuit switched connection may be provided by a GSMaudio connection of the GSM network. In a preferred embodiment of theinvention the packet switched connection 111 is used to transmit packetdata according to an internet protocol such as Transmission ControlProtocol (TCP).

The user device 102 may be, for example, a personal computer, a gamingdevice, a personal digital assistant, a suitably enabled mobile phone,or other device able to connect to the network 104.

In accordance with an embodiment of the invention the session node 106runs a communication instance 122 defining a session dedicated to a userof the user device 102. The communication instance 122 enables the userof the user device 102 to communicate across the communication network100. The session node 106 is able to concurrently run a plurality ofcommunication instances for a number of other users operating other userdevices (not shown).

The user device 102 runs a client software program 124 that provides aclient interface on the user device and allows the user of the userdevice 102 to communicate with the communication instance 122 running onthe session node 106.

The client program 124 running on the user device has a number ofdifferent components or layers for implementing various functions,including a protocol layer 402 (FIG. 2 a) for managing the interfacewith the GSM network. The interface with the GSM network will bedescribed hereinafter with reference to FIG. 2 b.

FIG. 2 a shows a protocol stack for the client program 124 according toan embodiment of the present invention. The protocol stack shows anoperating system layer 401, a protocol layer 402, a client engine layer404 and a client user interface layer 406. Each layer is responsible forspecific functions. Because each layer usually communicates with twoother layers, they are regarded as being arranged in a stack as shown inFIG. 2 a. The operating system layer 401 manages the hardware resourcesof the user device 102 and handles data being transmitted to and fromthe session node 106. The operating system layer also handles the databeing transmitted to and from the network 112. The client protocol layer402 of the client software communicates with the operating system 401.Processes requiring higher level processing are passed to the clientengine layer 404. The client engine 404 also communicates with the userclient user interface layer 406. The client engine may be arranged tocontrol the client user interface layer 406 to present information tothe user via user interface means of the user device and to receiveinformation from the user via the user interface means of the userdevice. The user interface means may comprise a speaker, a microphone, adisplay screen and a keyboard. This list is not exhaustive.

FIG. 2 b is a schematic diagram showing the transmission of data betweenthe client protocol stack and the GSM protocol stack in the user device102. As shown in FIG. 2 b the user device 102 further comprises a GSMprotocol stack 501 and a radio transceiver 502. Information transmittedfrom the GSM network to the user device is received by the transceiver502. The data received from the GSM network is processed by GSM protocolstack 501 before it is transmitted to the client program 124. Similarly,information to be transmitted to the GSM network from the client program124 is processed by the GSM protocol stack 501 before it is transmittedto the GSM network via the transceiver 502. The operation of the GSMprotocol stack 501 is known in the art and will not be described indetail herein.

Reference is again made to FIG. 1. As shown in FIG. 1 the peer to peersystem on the internet 104 comprises an inbound gateway 114 and anoutbound gateway 116. The inbound gateway 114 and the outbound gateway116 are connected to PSTN gateways 188 located in the PSTN networks. Theinbound gateway 114 is arranged to receive data for the peer to peersystem on the internet 104 from the PSTN gateways 188. The outboundgateway 116 is arranged to transmit data from the peer to peer system onthe internet 104 to the to the PSTN gateways 188.

Also shown in FIG. 1 is a profile node 128. The profile node 128 isresponsible for storing user profile information for users of the peerto peer system. The user profile information includes login informationfor logging into the peer to peer system and a contact list 132associated with each user of the peer to peer system. The contact list132 comprises the addresses of, for example, other users of thecommunication system stored as contacts by a user.

The communication instance 122 running on the session node 106 managesthe communication between the client program 124 running on the device102 and the peer to peer system on the internet 104. The communicationinstance may include a protocol adapter for handling communicationsusing different protocols. FIG. 3 shows the connection path between thecommunication instance 122 on the session node 106 and the clientprogram 124 running on the user device 102. As shown in FIG. 3, thesession node 106 further comprises a core module 205 for allocating acommunication instance 122 to a client program 124.

In accordance with an embodiment of the invention the client program 124running on the user device 102 is arranged to set up a connection withthe session node 106. The client program 124 sends the session node 106data relating to the user device 102 via the packet switched connection111 in a data packet. The data packet may include the attributes listedin table 1:

TABLE 1 KEY TYPE ATTRIBUTE CHUNKTYPE integer CLIENTDATADEVICE_PSTNNUMBER string device PSTN number in international notation.

As shown in table 1, the data packet includes an attribute defining anIP address of the user device and an attribute defining a PSTN number ofthe device. The PSTN address identifies the user device 102 in the PSTNnetwork 112.

After a connection between the client program 124 and the session node106 has been established the user of the user device may then providelogin information to the session node 106 in order to log into the peerto peer system on the interne 104.

The session node may verify the login information provided from the userdevice against the profile information for the user of the user device102 stored on the profile node 128. On verification of the logininformation provided from the user device 102 the core module 205 willassign a dedicated communication instance 122 to the client program 124.

The communication instance 122 associates the identity of the user ofthe user device, as defined by at least part of the login details of theuser, with the identity of the device. In one embodiment of theinvention the communication instance may store the identity of the usertogether with the identity of the user device in a data store 129associated with the communication instance 122.

According to an embodiment of the invention it is possible for the userof the user device to log into the peer to peer system using more thanone user device. According to this embodiment of the invention thecommunication instance will associate the identity of each device withthe identity of the user.

Once the session node 106 has assigned a communication instance 122 tothe user device 102 the communication instance 122 will provide theclient program 124 with data to enable to the client program toestablish a communication event with an entity in the communicationnetwork 100.

The entity may be any node in the communication system 100 that iscapable of receiving information from the user device 102. For examplethe entity may be another user device or a node in the communicationsystem 100. The entity may correspond to voice mail records, or otherdata records associated with the user of the user device.

Additionally an entity may be a node arranged to carry out controlcommands in the network.

An entity is located by an address in the network in which it resides.The address of an entity that resides in the internet 104 may be forexample an IP address, a URI

(Uniform Resource Indicator), a username, or a VoIP device. The addressof an entity that resides in the PSTN network may be a PSTN numberassociated with the entity.

In one embodiment of the invention the entity may relate to more thanone end point in the communication network 100. For example the entitymay be a user that is logged into the peer to peer system of theinternet using two or more user devices. In this case an entity willhave more than one associated addresses.

In accordance with an embodiment of the invention the user device 102may establish a communication event with an entity via more than onenetwork of the communication system. For example the user device 102 mayestablish a call using the PSTN network 112 to an entity located in theinternet 104.

In order to establish a communication event with an entity over morethan one network it is necessary to identify the entity in each network.

In accordance with an embodiment of the invention the communicationinstance 122 is arranged to allocate an identity to an entity that maybe transmitted and interpreted by both the PSTN network and the peer topeer system on the internet. In this case the identity of the entity maybe resolved to the address of the entity by a node located in theinternet 104. In a preferred embodiment of the invention the allocatedidentity is a PSTN number.

For example, if the entity is located in the internet, the public IPaddress of the entity in the internet will not be recognized by the PSTNnetwork. According to an embodiment of the invention the communicationinstance 122 is arranged to allocate a PSTN number to the entity thatmay be used to establish a call to the via the PSTN network. Theallocated PSTN number may then be resolved to the IP address of theentity at a location in the internet.

As shown in FIG. 1 a call manager 118 is connected to the session node106, the inbound gateway 114 and the outbound gateway 116. The callmanager has access to a data store 126. In FIG. 1 the data store 126 isshown as being associated with the call manager 118.

In the embodiment shown in FIG. 1 the call manager 118 is shown as beinglocated separately from the session node 106 and the gateways 114 and116. In alternative embodiments the call manager 118 may however formpart of either the session node 106 or of one of the gateways 114 or116. The logical connections between the call manager, the session node,the inbound gateway and the outbound gateway are shown in FIG. 6.

The call manager 118 is arranged to provide the communication instance122 with a PSTN number to be allocated to an entity in response to arequest from the communication instance. The communication instance isarranged to allocate the PSTN number to the entity and to provide theaddress of the entity to the call manager. The call manager is thenarranged to store the allocated PSTN number in the data store 126together with the address of the entity.

In a preferred embodiment of the invention the address of an entity maybe determined by the communication instance from the contact list 132provided from the profile node 128. This embodiment of the inventionwill be described with reference to FIG. 4.

FIG. 4 is a diagram showing the steps for allocating a PSTN number to anentity in accordance with a preferred embodiment of the invention.

In step S1 the communication instance 122 is arranged to retrieve theaddresses of the entities of that are listed as contacts in the contactlist 132 associated with the user of the user device 102. The addressesof the entities are retrieved from the profile node 128.

In step S2 the communication instance stores the address of each entityin the data store 129. In a preferred embodiment of the invention theentire contact list 132 is stored in the data store 129.

In step S3 the communication instance 122 is then arranged to retrieve aPSTN number for each entity listed in the contact list from the callmanager.

In step S4 the communication instance 122 is arranged to allocate eachPSTN number to each entity listed in the contact list and to report theaddress of each entity to the call manager, together with an indicationof which PSTN number has been allocated to which entity.

In step S5 the call manager 118 is arranged to store in the data store126 the address of each entity listed in the contact list in associationwith the allocated PSTN number.

In a preferred embodiment of the invention the call manager 118 isarranged to additionally store in the data store 126 the PSTN number ofthe user device 102 in association with the PSTN number allocated to theentity. The PSTN number of the device may be reported to the callmanager in either step S3 or step S4 by the communication instance. Inthis embodiment of the invention the address of the entity may beresolved using the PSTN number allocated to the entity and the PSTNnumber of the device. In this case one PSTN number may be allocated foruse by more than one user having a communication instance running on thesession node 106.

The allocated PSTN numbers may be stored in association with the addressof each entity and the PSTN number of the user device 102 for theduration of the session between the client program 124 running on thedevice 102 and the session node 106. A session is started when thesession node 106 assigns a dedicated communication instance 122 to theclient program 124. A session may be closed when the client program 124transmits a logout request to the session node, or when a session istimed out.

The contact list 132 together with the PSTN numbers allocated to eachentity in the contact list are transmitted from the communicationinstance to the client program 124. The contact list 132 and theallocated PSTN numbers may then be stored in a data store accessible tothe client program 124, located in the user device 102.

In a preferred embodiment of the invention the allocated PSTN numbersand the contact list 132 are transmitted to the client program 124 indata packets via the data connection 111. The allocated PSTN numbers maybe provided in a separate data packet from the contact list 132.

At least part of the PSTN numbers may be provided to the client programin a ‘call set up’ data packet comprising the attributes listed in table2:

TABLE 2 KEY TYPE ATTRIBUTE CHUNKTYPE integer CALLSETUP CALLMETHODinteger a numeric value identifying calling method to useDIALIN_NUMBER_PREFIX string first number in dial-in number range, forexample “+3725521000” DIALIN_NUMBER_RANGE_SIZE integer # of numbers indial-in block, for example 1000 VOICEMAIL_NUMBER_PREFIX string dial-innumber range for listening voicemails VOICEMAIL_NUMBER_RANGE_SIZEinteger # of numbers in voicemail number block

In one embodiment of the invention each PSTN number for calling anentity may be listed separately in the data packet. However in apreferred embodiment, each PSTN number may be determined by the clientprogram 124 from a first number corresponding to a ‘DIAL IN NUMBERPREFIX’ and a second number corresponding to an index number identifyingthe contact in the contact list (see table 3). The index number willfall within the number range, referred to as the ‘DIAL IN NUMBER RANGE’as shown in table 2.

The index number for each contact is transmitted in the contact listfrom the communication instance 122 to the client program 124.

Table 3 shows the attributes of the data packet containing the contactlist 132. Each entity in the contact list is given an index valuestarting from 1. The attribute container containing the contact list mayfurther include the contacts username, or URI for contacting the contactusing the peer to peer system, and the name of the contact.

TABLE 3 KEY TYPE ATTRIBUTE CHUNKTYPE integer ENTITY ENTITYINDEX integerentity index value, starting from 1 USERNAME string entity usernameFULLNAME string PSTNNUMBER string

The client program 124 may determine the PSTN number for each entity inthe contact list by arithmetically adding the first number to the indexfor the entity. For example if the first number is defined as: and theindex for an entity is:

33the PSTN number for the entity will be:+3725521053

Alternatively the client program may determine the PSTN number byappending the index to the first number. For example, if the firstnumber is:

+37255210and the index corresponding to an entity is:33the PSTN number for the entity will be:+3725521033

In one embodiment of the invention the call method attribute referred toin table 2 may indicate how the PSTN number should be determined fromthe information provided in the data packet. For example, the callmethod may specify whether the PSTN number should be determined byarithmetically adding the member of the number range to the firstnumber, or by appending the member of the number range to the firstnumber, or whether the entire PSTN number is listed in the data packet.

Accordingly, the PSTN number allocated to an entity may be determined atthe client program 124, the communication instance 122 and the callmanager 118.

In accordance with an embodiment of the invention the user device 102may establish a call to an entity located in the communication network100 via the PSTN network using the PSTN number allocated to the entity.The user device 102 may also receive calls from an entity located in thecommunication network via the PSTN network.

FIG. 5 shows the call connections made when placing calls between theuser device 102 and entities located in the communication network. Morespecifically FIG. 5 shows the following call connections:

(1) an outbound call from the user device 102 to an entity 110 b locatedin the PSTN network;

(2) an outbound call from the user device 102 to an entity 110 a locatedin the internet 104;

(3) an inbound call to the user device 102 from an entity 110 b locatedin the PSTN network; and

(4) an inbound call to the user device 102 from an entity 110 a locatedin the PSTN network.

As shown in FIG. 5, outbound calls made from the user device 102 to anentity are routed to the inbound gateway 114. The inbound gateway isthen able to determine the address of the entity by querying the datastore 126 via the logical connections illustrated in FIG. 6. The methodof calling an entity from the user device 102 will now be describe indetail in relation to FIG. 7.

A call comprises both a media data connection and a control data forhandling the call set up. In FIG. 7 the control data connection fortransmitting control data and the media data connection for transmittingthe media data are shown separately. The control data connection isshown as a solid line and the call connection is shown as a broken line.

In step S100 the user of the user device 102 initiates a call to anentity listed in the contact list 132. The contact list 132 may bedisplayed by the user interface layer of the client program 124 asselectable links on a display of the user device 102. The user mayinitiate a call to the entity by selecting a link for that entity. Whenthe user initiates the call the client program 124 is arranged to dialthe PSTN number allocated to that entity. The call placed by the clientprogram 124 will therefore include control data that defines theallocated PSTN number. The control data will also include the PSTNnumber of the user device 102. The dialled PSTN number allocated toentity is used to establish a media data connection and control dataconnection with the PSTN gateway 188 via the GSM audio connection 222.

In step 200 the media data connection is held at the PSTN gateway 188.The PSTN gateway 188 is arranged to transmit the control data to theinbound gateway located in the internet 104. The PSTN gateway 188 isarranged to transmit control data comprising recognised PSTN numbers tothe inbound gateway 114. The PSTN gateway may recognise numbers thathave been provided for use by the call manager 118 by the operator ofthe PSTN network.

In step S300 the inbound gateway 114 transmits the control datacomprising the allocated PSTN number of the called entity and the PSTNnumber of the user device to the call manager 118. The media dataconnection is held at the PSTN gateway 188 until the allocated PSTNnumber of the called entity is resolved to the address of the entity.

At step S400 the call manager 118 uses the PSTN number of the device 102to search the data store 126 for the contact list 132 associated withthe user of the device 102. The PSTN allocated to the entity is thenused to locate the address of the entity as defined in the contact list132. In one embodiment of the invention the call manager may alsoretrieve the username of the user associated with the user of the userdevice 102.

In step S500 the address of the entity is transmitted to the inboundgateway 114. The call manager 118 may also transmit the username of theuser of the user device 102 to the inbound gateway 114.

In step S600 the inbound gateway 114 accepts the media data from thePSTN gateway and uses the address of the entity received from the callmanager 118 to transmit the call via the packet switched network 104. Ifthe address of the entity is located in the PSTN network the inboundgateway will transmit the call to the PSTN network via the outboundgateway 116 (shown in FIG. 1).

In step S700 the call is received at the called entity, e.g. device 110a or 110 b. If the called entity is located in the internet 104 theusername of the user of the device 102 retrieved in step S500 may bedisplayed on the device 110 a to indicate the origin of the call.

In an alternative embodiment of the present invention the entity thatthe user of the user device 102 places a call to is not listed as acontact in the contact list 132. In this embodiment of the invention theuser device 102 is arranged to provide the communication instance 122with the address of the entity via the data connection 111 beforeinitiating a call with the entity. In this embodiment of the invention aPSTN number defined in the ‘call set up’ message described in relationto table 2 is reserved for an entity that is not listed in the contactlist. When the communication instance receives the address of the entityfrom the user device, the address of the entity is stored in the datastore 126 in association with the reserved PSTN number. A call may thenbe placed to the entity via the PSTN network in accordance with themethod steps described in relation to FIG. 7.

In a further alternative embodiment of the invention, for predefinedaddresses stored in the data store 126 the call manager is arranged toinstruct the inbound gateway to not accept the call and instead toprovide the PSTN gateway 188 with the address to route the call via thePSTN network. In a preferred embodiment these addresses may relate toemergency numbers e.g. ‘999’.

In one embodiment of the invention the address of an entity may specifythe location of a voicemail record associated with the user. The addressof a voicemail record may be determined using the username of the userand the address of a voicemail node. The address of the voicemail nodemay be prestored in the data store 126. Alternatively the address of thevoicemail record may be provided in the contact list associated with theuser.

In an further embodiment of the invention the address of an entity mayspecify a control command that may be implemented by a node. For examplethe address of the entity may define a specific action to be implementedfor the user's voicemail record by the voicemail node. For example thecontrol command may cause the voicemail node to delete all messagesstored in the user's voicemail record.

In one embodiment of the invention the communication instance isarranged to provide information relating to the geographical location ofthe user device 102 to the call manager 118 when requesting a PSTNnumber. In this embodiment of the invention the call manager is arrangedto provide the communication instance 122 with PSTN numbers that relateto PSTN gateways that are local to the user device, otherwise referredto as a local number.

In an alternative embodiment of the addresses of the entities having anallocated PSTN number may be stored at a data store associated with theinbound gateway. In this embodiment of the invention the address may beresolved at the inbound gateway.

In an alternative embodiment of the addresses of the entities having anallocated PSTN number may be stored at a data store associated with thePSTN gateway In this embodiment of the invention the address may beresolved at the PSTN gateway.

In an alternative embodiment of the invention the call data may be heldat the PSTN gateway until the address of the entity is resolved. In thiscase the inbound gateway 114 instructs the PSTN gateway to forward thecall data after the address of the entity is resolved.

While this invention has been particularly shown and described withreference to preferred embodiments, it will be understood to thoseskilled in the art that various changes in form and detail may be madewithout departing from the scope of the invention as defined by theclaims.

1. A method of transmitting a communication event from a calling entityto a called entity located in a communication system comprising a firstnetwork and a second network, the method comprising: determining a firstidentity associated with the calling entity and a first and secondidentity associated with the called entity, wherein the first identitiesare recognizable in the first network and the second identity isrecognizable in the second network; associating at a first node locatedin the second network the first identities with the second identity;establishing a connection between the calling entity and a second node;wherein the connection with second node is established using the firstidentity associated with the called entity; querying the first node withthe first identity associated with the called entity and the firstidentity associated with the calling entity to determine the secondidentity associated with the called entity; and transmitting thecommunication event to the called entity using the second identityassociated with the called entity.